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I have this 2002 Forester with 265K miles that has been stuttering/sputtering in the last month or two.  When the timing pulley failed, we had the machine shop do the half of the engine showing the low compression.   I'm not getting other codes connected to performance, evaporative cannister, etc., just the p130, which is the front oxygen sensor. I'm getting some oil burning puffs, say when I'm going downhill on the uphill acceleration, burns oil then which I assume is valves.   I've changed out the plug wires and ignition coil; I pulled a couple plugs which are ok, the plugs have always been fine.   Any thoughts would be appreciated.  I'm thinking the p130 may be indicative of excess exhaust possibly a threat to the cat. converter.  

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When you say the machine shop did the side of the engine showing the low compression, did they just replace the valves? Or did they replace pistons and rings too? 

If they did pistons and rings, what condition were the two from the repaired side of the engine in? 

Asking as my L series used to drive awesome until you coasted for a period of time then got back on the throttle again. The worst situation was a long down hill section off throttle - back on the throttle again it was a smoke screen out the back! Replacing the PCV valve didn’t fix it. From memory the issue was cracked ring landing between the lower compression ring and the oil rings. 

I’m not saying this is the issue, anything is possible though. 

Changing your PCV valve could help. Sounds more likely that you’ve got stuffed or incorrectly fitted (stuffed!) valve stem seals. 

The vacuum generated at high revs with the throttle closed could pull quite a bit of oil past a damaged valve stem seal, especially on the intake valves. 

Not what you want to hear, this is one thing that could cause the symptom you’re experiencing. 

Cheers 

Bennie

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Posted (edited)
15 hours ago, el_freddo said:

When you say the machine shop did the side of the engine showing the low compression, did they just replace the valves? Or did they replace pistons and rings too? 

If they did pistons and rings, what condition were the two from the repaired side of the engine in? 

Asking as my L series used to drive awesome until you coasted for a period of time then got back on the throttle again. The worst situation was a long down hill section off throttle - back on the throttle again it was a smoke screen out the back! Replacing the PCV valve didn’t fix it. From memory the issue was cracked ring landing between the lower compression ring and the oil rings. 

I’m not saying this is the issue, anything is possible though. 

Changing your PCV valve could help. Sounds more likely that you’ve got stuffed or incorrectly fitted (stuffed!) valve stem seals. 

The vacuum generated at high revs with the throttle closed could pull quite a bit of oil past a damaged valve stem seal, especially on the intake valves. 

Not what you want to hear, this is one thing that could cause the symptom you’re experiencing. 

Cheers 

Bennie

I will ask them, what is customary?  The machine shop charged $250 for the half of the engine they worked on.

 

I was getting the following codes before I erased them:  p130, 447,452,171, 107.   Some of those could have been the result of the loose battery cable.  Now just evap. system and 130.   

I just ordered a PCV, will see if it makes any difference.   I pulled the rubber hose off and it seemed as if there was a fair amount of oil below the rubber hose intake.

Edited by ThosL
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Posted (edited)

So, the O2 sensor (front one) replacement is not indicated?  It would not cause the sputtering/stuttering?

Updated; changed out the PCV, no real difference.   

Car is fine until it warms up, then the sputtering, so probably heat related or sensor.

Edited by ThosL
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  • 1 month later...
Posted (edited)

 Put in an Amazon MAP sensor earlier in the year, could have failed; just google symptoms on these failing.  I changed it out again, no  big difference; will try the spark plug extender so the p420 code is addressed.

Edited by ThosL
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  • 2 weeks later...

Also changed out the downstream O2 sensor earlier today, runs a lot better now, no sputtering!   The old sensor was carboned up/black soot.  New one does not have an opening that I can see.

Edited by ThosL
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